One year analysis of a new stainless steel spiral Schlemm’s canal expander in open-angle glaucoma

Session Details

Session Title: Glaucoma I

Session Date/Time: Sunday 14/09/2014 | 08:00-09:30

Paper Time: 08:54

Venue: Auditorium

First Author: : G.Dushina RUSSIA

Co Author(s): :    V. Kumar   M. Frolov   E. Bozhok   A. Bezzabotnov     

Abstract Details

Purpose:

To evaluate the safety and efficacy of a new stainless steel spiral Schlemm’s canal expander (SCE) in decreasing intraocular pressure (IOP) in patients with open angle glaucoma (OAG).

Setting:

Ophthalmic unit of Skhodnya city hospital, Moscow region; Department of Ophthalmology, People’s Friendship University of Russia, Moscow, Russian Federation.

Methods:

Between October, 2012 and March, 2013 in a prospective interventional case series study SCE made from 0.05mm thick medical grade stainless steel wire was implanted in SC of 12 patients (6 male and 6 female; average age – 73.7+/–7.2 years) suffering from OAG. Out of these in 5 cases a combined procedure was performed for coexisting pathology. In 2 patients with end stage OAG, SCE was implanted to serve as an organ saving operation. To implant SCE 3 mm of SC was exposed ab externo without creating a window in descemete membrane and a segment of its unexposed part was dilated with cohesive viscoelastic and microprobes followed by insertion of SCE. Wound was closed water tightly. The SCE was 5-6 mm long, it's inner lumen diameter was .2mm, outer - .3mm. Inclusion criteria were OAG having high IOP on maximum hypotensive medication(s) and minimum follow-up period not less than 12 months. Outcome measures were IOP change, number of glaucoma medications pre- and postoperatively and complications. To assess success rate World Glaucoma Association guidelines were used. A paired t-test was used for IOP and medication analysis. Results were significant when p<0.05. Follow up visits were at 3, 6 and 12 months.

Results:

Mean preoperative IOP was 25.1+/–6.5mmHg (95%CI 24.1-26.2) and mean number of medications - 2.4+/–0.9 (95%CI 2.3-2.6). At 12 months, there was a reduction in mean IOP by 46.1+/–16.8% and IOP decreased to 13.4+/–6.0mmHg (p=.00006; 95%CI 12.4-14.3). Use of medications reduced to 1.1+/–1.2 (p=.002; 95% CI .9-1.3). An IOP =<18mmHg was achieved by 41.7% (5/12) cases without use of hypotensive medications and by 66.7% (8/12) with at least one medication. 8.3% (1/12) needed at least two medications and 25% (3/12) – three medications. Intraoperatively, microperforation of trabecular meshwork (TM) in areas other than exposed part of SC occurred in 25% (3/12) cases. In these cases one end of SCE was lying in anterior chamber angle without contact with intraocular structures. Postoperatively, specific complications related to SCE were rare. In one case the body of SCE ruptured TM because of extra pressure put on eye ball while inserting goniolens. Both ends of the expander were embedded in SC. Patient’s IOP was under control with one medication. In another case YAG laser trabeculopuncture was required to control IOP. During the follow up period not a single case of inflammation at insertion site, of hypotony, or shallow chamber was observed.

Conclusions:

Lately much interest is seen in Schlemm’s canal surgery. This interest is motivated by evidence that the elevated IOP in glaucoma is due to an increased resistance to outflow, and that the majority of resistance is present in the juxtacanalicular connective tissue of the TM including the inner wall of SC. Canaloplasty uses the natural aqueous outflow pathways to reduce IOP. For the success of canaloplasty circumferential viscodilation of SC, placement of 10-0 suture, proper tensioning of SC and watertight suturing of flaps are mandatory. But if a tension suture can be placed, an IOP decrease around 10 mmHg might be expected. However placement of tension suture 360 degree disturbs Johnstone’s intracanalicular structures, whose role in aqueous drainage is not yet well understood. In the presented case series only a segment of SC was dilated and SCE was inserted to keep this segment permanently dilated. One year analysis shows that this procedure significantly decreases IOP from base line to 13.4 mmHg at 12 months follow-up accounting for reduction in IOP by more than 46%, demonstrating that procedure may be helpful as well in advanced cases where maximum reduction in IOP is required in order to preserve visual functions. Additional to the IOP lowering effect, a significant decrease in the number of ocular medications was also observed in our series. The difference was statistically highly significant. Complications were few and easily manageable. In spite of shortcomings of this study - small sample size, and uncontrolled, non-randomized and non-comparative nature, it can be concluded that segmental dilation of Schlemm’s canal using a new stainless steel spiral Schlemm’s canal expander is safe and effective in decreasing intraocular pressure significantly in patients with open angle glaucoma.

Financial Interest:

NONE